Monday 6 July 2009 17.00 EDT
First published on Monday 6 July 2009 17.00 EDT

"Let me ask you something," says Jimmy Shaw, leaning across the table. "If the record were called Distance, do you think it would have a different energy?" We are in a bar discussing Metric's recent album, a startlingly buoyant record that, at the very last moment, had its name changed from Distance to Fantasies. "Whatever you call an album, you leave that colour in every single song," explains Shaw's fellow band member Emily Haines.

Fantasies, the Canadian quartet's fourth album, is their most uplifting work to date. The grungy, spiky anger of Live It Out, which proved a slow-burn success in 2006, has been replaced by a breezy optimism – a sound, as anyone who saw the band at Glastonbury this year will attest, that is perfectly suited to big-scale performances. "I wanted the record to feel like how it sounds when you're at a festival and you're at the back, and the sound is drifting towards you and you can make out everything," says Haines. "It's not about being in a sweaty club. We made that record already."

Metric formed in New York in 1998, with Haines on synthesiser and vocals, and Shaw on guitar; the band now has Josh Winstead on bass and Joules Scott-Key on drums. Their sound is fiercely poppy, often uncompromisingly female (one song is called Patriarch on a Vespa) and itching for a fight.

Haines is fast developing a reputation as one of today's most charismatic and surprising rock singers. At live shows, audiences fall into two categories: swooning men, and women who want to be just like her. Based in Toronto, they are one of many bands that circle the musical collective Broken Social Scene, which gave birth to Feist. In 2007, Haines released a solo record, Knives Don't Have Your Back, a melancholy set of songs so different to her Metric work that many wondered if she would ever return to the band.

"There was an amazing moment a couple of years ago," Shaw says, "at a place in Toronto called Harbourfront, a beautiful amphitheatre. Emily was playing there. There was a string quartet on stage, her on piano – and thousands of people watching. She gets to the last song in the set, and it's a sad song, like most of the material. She got halfway through the first verse and then mumbled to the band, 'Everybody go to the end!' So they went to the end of the song. 'Thank you everybody,' she said. 'I don't really want to feel that emotion any more.' And I turned to the person next to me and said, 'That's the end of Emily's whole solo thing, right there.'"

When Haines began writing material for the new Metric record, she took off to Buenos Aires for inspiration."My life was yielding nothing," she says. "I just had to go some place. I was looking for rooms that had a piano in them, literally typing into Google: piano room rent." She laughs. "I found a place in Buenos Aires, an old French-style apartment, with a Steinway." The relocation had a transformative effect. "As soon as I got there, I felt it," she says. "These people listen to all these different kinds of music. I felt, 'I love music!' How did this fact ever escape me?"

Metric spurned major-label deals in order to self-release Fantasies. "We're surrounded by people saying, 'You guys can be huge. Come with us and I'll give you the world!'" Haines gives a bemused smile, recalling the many occasions that industry executives falsely promised the band such super-stardom. "But I can't live my life feeling hard done-by that I'm not Beyoncé."

The last couple of years have given the band a sense of pride. "We haven't compromised ever," says Haines. "We've made everything work with our own hands, played with the Rolling Stones, and played to thousands all over the world."

So is this the reason for the upbeat feel of Fantasies? Haines laughs: "It's funny that you cringe when you say 'upbeat', because that's what I do as well. We talked about it as a band, like what's the fear of actually making something that sounds beautiful and makes you feel good? Why are we only interested in making people feel just a little bit stressed out?"

Shaw smiles. "Why does there always have to be puke on the wall in rock'n'roll?" he says. "And why," asks Haines, "do we always have to do photoshoots in front of fences and graffiti? It's all part of the same thing. Upbeat doesn't make me cringe now. In music that's really transcendent, there's real happiness. I think we tried to let a little bit of that into our lives – just a taste, you know, to see what it it felt like? And I really enjoy it."

Fantasies is out now on Metric Music International. The single Gimme Sympathy is released on 27 July. Metric play the Reading festival on 29 August.

• This article was amended on Tuesday 7 July 2009. The band's name is Metric, not Metrics. This has been corrected.